None of my guns have night sights on them. The only experience I have with night sights (I swear I'm not making this up) was when a guy at Rampart Range let me shoot his reproduction Hawken Rifle that he had installed night sighs on. I do remember how distinct the sights were.
I carry my Glock 26 mostly at night. I'm going to replace the factory plastic sights on it anyway so are night sights worth the extra money? Are they considered an essential modification?